Pyrroloquinoline quinone grafted carboxymethyl chitosan with oxidized xanthan gum hydrogel for biomedical applications

The present study was devoted to the construction of a polysaccharide-based Schiff base composite hydrogel system for pyrroloquinoline quinone (PQQ) delivery. Carboxymethyl chitosan (CMCS), a water-soluble modification of chitosan, has demonstrated considerable potential in advancing innovative drug delivery methods, primarily due to its favorable physicochemical properties and biocompatibility. Oxidized xanthan gum (OXG) has been widely used in the field of biomaterials due to its good biocompatible properties. PQQ was grafted onto CMCS by covalent bonding in the EDC/NHS system to form PQQ-g-CMCS copolymer, which was subsequently crosslinked with OXG by dynamic Schiff base reaction to prepare a composite hydrogel with a dual network structure successfully. The grafting reaction of PQQ with CMCS and the formation of Schiff base bonds were verified by FT-IR, and the porous structure of the hydrogel was confirmed by SEM observation. By in vitro degradation, swelling tests, and rheological as well as mechanical property analysis, the PQQ-g-CMCS/OXG hydrogels exhibited certain biodegradability, rapid swelling properties, enhanced the network densification and long-term release effects. In addition, the cellular assay also proved that the hydrogel has no significant toxicity, providing a new idea for research in the field of biomedicine.